The present invention relates generally to light controlling systems and more particularly to an improved sensing system for use with a photographic flash device.
Electronic photographic flash systems are known in the art in which a flash of light produced by the flash tube of the system is automatically terminated by a light responsive sensing device after a predetermined total quantity of light has been received from the scene being photographed.
In the prior art photographic systems, a light sensing device is generally mounted on or formed as a part of the flash device which in turn is connected to a camera via a standard two conductor connection therebetween. However, distinct advantages may be obtained by a photographer when the light sensing device of the flash system is used as an independent member of the system, detached from both the camera and the flash device, as shown in U.S. Pat. No. 3,774,072 issued to Francis T. Ogawa, on Nov. 20, 1973.
However, it would be beneficial to provide both a light sensing device secured within the flash device and a light sensing device capable of being remotely located from the camera. With the provision of two sensors which are selectively operable by the photographer, the photographer obtains the capability of using either sensor as he desires to produce photographs.
With such a two sensor system, however, the fixed sensing device must be deactuated when using the remotely positionable sensing device. It would be beneficial, also, if the external sensing device would require only a two-wire standard connection for communication with the flash.
It is, therefore, an object of the present invention to provide an improved photographic flash system.
It is also an object of the present invention to provide a flash system having a fixed and a non-fixed sensor, selectively operable by the photographer.
It is a further object of the invention to provide an external sensor connectable by two wires to a flash control circuitry having an internal sensor. The connection of the external sensor automatically disables the internal sensor's control of flash duration.